Turbine driven multistage compressor



J. A. N. GALLIOT TURBINE DRIVEN MULTISTAGE COMPRESSOR 2 Sheets-Sheet 1July 21, 1953 Filed May 18, 1949 Jules Andr a Norberl Galliol y 1, 1953J. A. N. GALLIOT TURBINE DRIVEN MULTISTAGE COMPRESSOR 2 Sheets-Sheet 2Filed May 18, 1949 ITnfenEw Juies Andre Nor-her! Gallz'ot M y m c IIorngys Patented July 21, 11 953 TURBINE DRIVEN MULTISTAGE COMPRESSORJules Andre Norbert Galliot, Bexley, England Application May-18, 1949,Serial No. 98,922 In France May 21; 1948.

This invention relates to gas turbines such as employed forjet-propelled aircraft and like pur-' poses."

The invention relatesmore particularly to gas turbines as described inmy pending patent application Serial No. 730,446, filed February 24,

6 Claims. (01. 230-116) turbine.

1947, Patent No. 2,60i),235, issued June 10, 1952.

The main objects of the present invention are to provide means forobtaining higherpoweroutput from the turbine and to reduce theweight ofthe rotating parts.

More specifically, the invention has for object to lighten the turbinerotor by making it of a light alloy having a specific weight or densityof about 4 or less, the-use of such material being made possible byintensive cooling of the turbine blades and connected parts.

Another object is to provide for higher compression of the air deliveredto the combustion chambers, by arranging'for multi-stage compressionpreferably with inter-stage cooling and with final heating of thecompressed air supplied to the combustion chambers. 1 r

Other objects and advantages of the invention will hereinafter appearfrom the followingfde scription, given with reference to theaccompanying drawings, in which:

Fig. 1 is a diagrammatic viewof one half being in longitudinal sectionandthe other half in elevation. v i Fig. 2 is an enlarged end viewfroin'the left of Fig. 1, with parts broken away on the right to showthe interior of one compressor andits outletconnecti'ons, and" on theleft to show the interior of the other compressor and ,itsconnec tions.

Fig. 3 is a half-section of the centrifugal compressors at one end ofthe turbine.

Fig. 4 is a perspective view of one of the turbine blades with theassociated vane element of a primary compressor.

Fig. 5 is a sectional detail and wheelspoke. V

Referring to Fig. 1, theturbine shaft If} is fitted at one end with adriving wheel H having external blades 12 against which hot gases aredirected by guide vanes IS, the gases being delivered from combustion.chambers l4 spaced around the shaftand extending approximately of theturbine blade parallel to its axis. The central portion ofthe turbinewheel I l is apertured by providing it with spokes or webs which areshaped as helicoidal the turbine,

similarly enlarged view showing a turbine wheelfrom the interior of anouter cas-- ing 16, the open end ll of which faces the direction offlight of the aircraft driven by the Within the casing, the coldincoming air passes between and along the outside of the combustionchambers hi to the rear end'of the casing, where it is deflectedinwardly to pass between a plurality of ducts lilconveying the exhaustgases from the turbine to the jet outlet 19. v The air passages arepreferablyof oval or streamlined sectionto allow the deflected air toflowfreely between-the ducts lB'and substantially in'a radial direction,after which the air travels forwards through a'fixed grid 28 includingannular guide vanes to the rotating vanes l5. After passing through thelatter, the air encounters another set of guide-vanes 2| formed byradial arms supporting the'turbine stator 22,

these vanes or arms and thefixed grid 2!] carrying bearings 23 fortheshaft l0.- 7 Beyond the guide vanesZI there is arranged a multi-stageaxial-flow compressor composed of alternate rotor blades 24 secured torings 25 fixed I I onthe shaft l0 and stationary blades 26 fixed insidean induction tube'2'l, the outer wall of which is insulated against theheat of the 'com-.

bustion chambersf'M by inserts 28 of suitable material. compressorblades 24, '26 being-of gradually decreasing height until near theforward end of the tube, where the last set of'stationary blades 26 areshaped to give a sharper taper whereby the-partly compressedair is ledinto the eye or intake 29 of a centrifugal compressor 3G secured uponthe shaft; this compressor 39 has its runner madeintegral with that ofanother centrifugal compressor 3 l, the two runners being placed ing ofthe main compressor -30 and are then curved over forwardly and inwardlytowards the intake 33 of the othercompressorfwhere the gases enter witha tangentially velocity component; these relatively long'branches 35 maybemade initwo lengths connected by flanged joints The tubeZ'l tapers indiameter, the

36 to facilitate manufacture and erection, and the exposed lengthsleading to the intake 33 are preferably ribbed externally or providedwith gills 31 or the like (as shown in Fig. 2, in one instance) forcooling purposes.

The final compressor 3|, being supplied with air already compressed inthe previous stages and preferably cooled as stated before transfer tothis final stage, can be made of smaller capacity and of a diameterconsiderably less than the main compressor; the manifold 34, into whichthe finally compressed air, is. delivered, can therefore be of smallerdiameter at the joint-- ing surfaces 38 than the first manifold 32: seeFig. 3. This second manifold intakev 34. is con veniently made oftoroidal annular, shape, as seen more clearly in Fig. 2 with alternateinlets 39 and delivery branches 40 respectively, ar-

ranged obliquely to its cross-section, as seen in.

Fig. 3; thus the compressed air passing through ittravels for a shortdistance circumferentially from. each inlet 39. to, the next deliverybranch 49, and with a helicoida-l swirling motion inside the manifold.The delivery branches or connectors 40 of this second manifold willextend more or less tangentially and in the samev direction around theaxis of the shaft It] as the branches 35 from the main compressor 30,but in a different plane, so that as they curve over rearwardly of theaircraft to connect with the respective combustion chambers l4, they canbe located alternately between the'respective forwardly curving branches35 of. the first manifold, the two sets of branches 35; 40- thuscrossing without interference. The air may be caused to slow down insidethe second manifold by increasing the cross-sectional area of. thelatter relative to the area of the inlets: 39', thereby converting partof its kinetic energy into pressure.

Within the second manifold: 34,. and: extending either continuously'oratintervals; around its circumference, suitable heating means are provided, for example in the. form of an: electrical and is also heated bythe electrical resistor coil 4| before delivery from the branches 48leading into the respective combustion chambers, these branches beingheat insulated to retain the heat of the air; as the heating is appliedto pure air, there is no danger of ignition within the manifold 34 orits branches 40.

The increase of pressureof the. compressed air reduces the overall sizeor bulk of the combustion chambers and turbine, and also leads to fueleconomy suflicient to olfset the small amount of energy consumed inheating the air within the second manifold 34, which is kept as hot aspossible by external lagging (not shown). Fuel is suppliedtothe-combustion chambers l4 through injectors of known kind (not shown),the supply of, fuel being effected by the auxiliary mechanism 50indicated in Fig. 1.

The number of branches of both manifolds 32, 34 will be made equal tothe number of combustion chambers M to be supplied, for example nine, sothat the branches of each manifold can be inter-spaced between those ofthe other, the delivery branches 40 of the secondv manifold crossing thefirst manifold at the points between its branches 35. The air from themain compressorifl has its temperature lowered by the inter-stagecooling effected by the ribbed or gilled branches 35- of the firstmanifold which is kept as cool as possible; these branches arepreferably cooled by the air entering the casing is, this air being thusslightly pre-heated so as to reduce the risk of icing up the primarycompressor.

It will be understood that the above-mentioned values of the compressionin the various stages are given merely by Way of example and that theproportional values of the three stages resistor such as a coiled wire4!, as shown on the left of Fig. 2; this resistor coil may be raised tored heat by passage of a current supplied by a generator (not shown)driven by the turbine.

Assuming that the atmospheric air entering by ram effect into; the openend '21 of thecasing,

and preheatd slightly by the combustion chainpressor 30, the lattercanbe designed to raise V the compression to about 3. atmospheres,instead of the more usual pressure of about 4 atmospheres required forfeeding the combustion chambers 14; the main compressor can thus be madeof smaller size than if it had to produce the final pressure. The airdelivered by this main compressor 30 is then conveyedthrough theconnected manifold 32 and its branches 35 to the eye or intake of theother compressor 31 mounted in front of the former; this othercompressor 3|, being supplied with air at a pressure of 3% atmospheres,can be made of still smaller diameter, while serving to compress the airto a final pressure of about 5. atmospheres for feeding the combustionchambers [-4. This air is conveyed through the second manifold 34,wherein it is allowed to slow down; slightlyso as to convert part. ofits kineticv energy into, pressure,

of compression may also be varied.

The turbine rotor, comprising the driving wheel H, the rotating blades24 of. the axialfiow compressor, and the main and final compressors 38,3|, are made of-a light. alloy having a specific weight preferably lowerthan 4, as compared with the specific weight of about 8 in the case ofaustenitic steel and alloy steels with a high nickel-content, ashitherto employed, which steels are comparatively poor conductors ofheat. Among the light alloys to be used, there may be mentionedHidum-iniumg of a specific weight of 2.85, capable of withstanding atemperature of 400 C., and possessing excellent thermal conductivity,the particular alloy preferred being that known as RR-57, an alloy ofoutstanding merit for use at temperatures in therange 2'75-400 C., andhaving the following chemical composition:

Copper Silicon 0.2% max. Iron 0.3% max. Manganese 0.2-0.3% Titanium,0.1-0.15% Aluminum Remainder the turbine ,wheel ,or otherwise forciblycooling the rim, blades and central portion or'spokes.

In the present case; the incoming air entering through the turbine wheelll, after preliminary heating inside the casing Iii, by contact; withthe combustion chambers l4'and-exhaustdii'cts [8, will have atemperature lower than- 200 C., so that it is capable of effectivelycooling "the wheel by means of the vane-forming spokes or webs I5.Moreover, this air is subject. to centrifugal force inside the wheel H,causing it to press against the interior of the rim connecting the vanes[5 to the external turbine blades l2; by forming air passageswithinatheseblades to admit the air from the interior of the wheel, theair can be-made'to flow outwardly through the blades in sufficientquantity to maintain their temperature at or below the .safe workingfigure of 400 C.

Fig. 4 illustrates one of the turbine wheel spokes comprising theturbine blade I2, the primary compressor vane I5, a connecting segment42 of the wheel rim, and a root element 43 of wedge shape having teeth44 whereby the several spokes are rigidly clamped together at the wheelhub in the assembled position, as seen in Fig. ,1. The rim segments areformed with alternate mortises and tenons 45, 46, which interengage withthose of the adjacent segments, and are grooved at 41 toreceive'clamping rings 48 or the like. A number of holes 49 are drilledlongitudinally through the turbine blade l2, so as ploy light alloyswhich could not otherwise withstand the heat of the gases from thecombustion chambers i l, but also secures other accessory advantages.

For example, the construction of thejturbine rotors from light alloys,owing to the reduction of weight which it involves, allows of improvinggreatly the accuracy of aim when firing guns mounted upon single-seateraircraft. Upon the latter, which are generally unstable at high speeds,the gyroscopic effect due to the turbine rotors produces undesiredoscillations,a circumstance which renders it difficult to maintaindirection of flight within a few seconds of angle forfiring the gunduring thefugitive moments when the target comesinto the line of fire.The gyroscopic effect is in practice greatly reduced owing to thereduction of mass of the rotors constructed in conformity with theinvention.

The invention canbe applied for example to the rotors of gas turbinessuch as describedinmy pending patent application Serial No. 730,446,

in United States Patent No. 2,600,235, in which guide vanes"co-operating with saidspoke-form ingvanes and a plurality ofaxial-compressor rotors in'series with said primaryistage, and asintermediate and final compression stages two centrifugalcompressors'mounted on said 'shaft and operating inseries, atubularcasing :around said shaft conveying air from said priinary' compressionstage to said intermediate compression stage, and a plurality of tubularconnectors in parallel conveying air between said intermediate and finalcompressionstages.

2. Ina gas turbine including a rotary shaft anda bladed wheel securedthereon, a multistage air-cornpre'ssor comprising as primary andoperating in-series, a tubular*caSing' ai'ound said shaft conveying 'airfrom said primary compression stage to said intermediate compressionstage, and a plurality of tubular connectors in parallel conveying airbetween said intermediate and final compression stages, and means forguiding said air into external contact with said connectors before beingadmitted to said primary compression stage.

3' In a gas turbine including a rotary shaft and a bladed wheel securedthereon, a multias intermediate and final compression stages twocentrifugal compressors mounted on said shaft and operating in series, atubular casing around said shaft conveying air from said primarycompression stage to said intermediate compression stage, and aplurality of tubular connectors in parallel conveying air between saidintermediate and final compression stages, external cooling gills uponsaid connectors, means for guiding air into contact with said gillsbefore admission to I said primary compression stage, a manifoldreceiving air from said final compression stage, and a plurality ofbranches being equal in numher to said connectors and also from saidmanifold conveying the finally compressed air, said branches beinginterspace'd angularly between said connectors.

4, In a gas turbine including a rotary shaft and a bladed wheel securedthereon, a multistage air-compressor comprising as primary compressionstage a plurality of helicoidal vanes forming spokes of said wheel, withstationary guide vanes (Io-operating with said spoke-forming vanes, andas intermediate and final comturbines the greater part or the. whole ofthe cold air' admitted forcompression to feed the combustion chamber orchambers is caused to pass through the rotorwith a view to increasingthe cooling of the latter.

' stage air-compressor comprising as primary compression stage aplurality of helicoidal vanes forming spokes of said wheel, withstationary It is however to be understood'that the invention is notlimited to pression stages .two centrifugal compressors mounted on saidshaft and operating in series. a tubular casing around said shaftconveying air from .said primary compression stage to said intermediatecompression stage, and a plurality of tubularfconnectors' in parallelconveying air between said intermediate and final compression stages,external cooling gillsupon said connectors, means for guidingair intocontact with said gills beforeadmission to said primary compressionstage, a manifold. receiving air from said final compression stage, anda plurality of branches from said manifold, conveying the 7 finallycompresseq air, said connectors. being curved over the exterior? of.said manifeld. and said branches. being equal; in number to saideonnecters, and also being interspaced angularly between said;connectors.

5. In a gas turbine including; a rotary: shaft,

a. bladed wheelsecured thereon, and a multi-,

stage. air-compressor as specified in, claim 1, a turbine Wheel made ofa light aluminum alloy of high thermal conductivity, said wheel havingits blades integral. with. its spoke-forming;- vanes, and said. vanes:being exposed to the air traversing aid: primary cempression st e- 6.In; a gas turbine including; a rotary shaift. a bladed, wheel. se uredthereon, and, a multir sta e. alr compressor" as specified, claim 1, aturbine. wheel; made of Hiduminium alloy havin a: specific weight lower:than 4 and a Safe work;- ing. temperature limit of about, 400,? saidwheel having: its, blades integral Withits spokes,- fqrming vanes, and;said vanes being exposed to the airtraversing said, primary compressiensta e- V NQRBERT GALL QT.

Number Number Name Date Griflith Dec.v 25, 1495 Youngash Mar. 5 1946Heppner' Apr. 9, 1946 Halford June 11, 1946 Baumann Nov. 12, 1946Pavlecka Jan. 21, 1947 Heppner Sept. 30, 1947 Bedding Aug. 10, 1948=Shu1er May 3, 1949 Stalker Nov.,29, 1949 FOREIGN PATENTS Country DateGreat Britain Jan. 29, 194?

